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Nilotinib treatment in mouse models of P190 Bcr/Abl lymphoblastic leukemia.

Kaur P, Feldhahn N, Zhang B, Trageser D, Müschen M, Pertz V, Groffen J, Heisterkamp N - Mol. Cancer (2007)

Bottom Line: In addition, culture of such cells ex vivo showed that they were as sensitive as the parental cell line to nilotinib but that the presence of stromal support allowed resistant cells to grow out.Visible lymphoma masses disappeared within six days of treatment and leukemic cell numbers in peripheral blood were significantly reduced.These results show that nilotinib has very impressive anti-leukemia activity but that lymphoblastic leukemia cells can become unresponsive to it both in vitro and in vivo through mechanisms that appear to be Bcr/Abl independent.

View Article: PubMed Central - HTML - PubMed

Affiliation: Section of Molecular Carcinogenesis, Division of Hematology/Oncology, Saban Research Institute, Childrens Hospital Los Angeles and the Keck School of Medicine, University of Southern California, Los Angeles, California, USA. pavinder@gmail.com

ABSTRACT

Background: Ph-positive leukemias are caused by the aberrant fusion of the BCR and ABL genes. Nilotinib is a selective Bcr/Abl tyrosine kinase inhibitor related to imatinib, which is widely used to treat chronic myelogenous leukemia. Because Ph-positive acute lymphoblastic leukemia only responds transiently to imatinib therapy, we have used mouse models to test the efficacy of nilotinib against lymphoblastic leukemia caused by the P190 form of Bcr/Abl.

Results: After transplant of 10,000 highly malignant leukemic cells into compatible recipients, untreated mice succumbed to leukemia within 21 days, whereas mice treated with 75 mg/kg nilotinib survived significantly longer. We examined cells from mice that developed leukemia while under treatment for Bcr/Abl kinase domain point mutations but these were not detected. In addition, culture of such cells ex vivo showed that they were as sensitive as the parental cell line to nilotinib but that the presence of stromal support allowed resistant cells to grow out. Nilotinib also exhibited impressive anti-leukemia activity in P190 Bcr/Abl transgenic mice that had developed overt leukemia/lymphoma masses and that otherwise would have been expected to die within 7 days. Visible lymphoma masses disappeared within six days of treatment and leukemic cell numbers in peripheral blood were significantly reduced. Treated mice survived more than 30 days.

Conclusion: These results show that nilotinib has very impressive anti-leukemia activity but that lymphoblastic leukemia cells can become unresponsive to it both in vitro and in vivo through mechanisms that appear to be Bcr/Abl independent.

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Analysis of nilotinib in a transgenic mouse model of terminal leukemia/lymphoma. (A), Five P190 Bcr/Abl transgenic mice were treated with 75 mg/kg nilotinib daily upon visible signs of lymphoma for a period of 30 days. This image shows one of the five mice treated with the drug. Arrows point to the dramatic reduction in the size of the lymph node swelling/lymphoma over a period of six days of treatment. (B), Survival after diagnosis of overt leukemia/lymphoma. Numbers to the left indicate individual identifiers of the transgenic mice. The arrow points to the first diagnosis of leukemia/lymphoma. The black line represents time to leukemia (days), the grey bars the period of treatment with nilotinib and the white bars time to death after no treatment. (C), Peripheral blood of two wild type (Wt) littermates; two overtly leukemic P190 Bcr/Abl transgenic mice before treatment and the same mice after 7 days of 75 mg/kg nilotinib treatment. Dead cells were excluded based on propidium iodide uptake and the analysis was restricted to living mononuclear cells by forward and side scatter gate settings. Antibodies are as indicated. (D), Percentage of peripheral blood cells that had cell surface expression of CD19 and high levels of AA4.1. Bars, ± SEM. Wild type, n = 3; preleukemic, n = 3; leukemic, n = 3; nilotinib-treated, n = 2.
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Figure 3: Analysis of nilotinib in a transgenic mouse model of terminal leukemia/lymphoma. (A), Five P190 Bcr/Abl transgenic mice were treated with 75 mg/kg nilotinib daily upon visible signs of lymphoma for a period of 30 days. This image shows one of the five mice treated with the drug. Arrows point to the dramatic reduction in the size of the lymph node swelling/lymphoma over a period of six days of treatment. (B), Survival after diagnosis of overt leukemia/lymphoma. Numbers to the left indicate individual identifiers of the transgenic mice. The arrow points to the first diagnosis of leukemia/lymphoma. The black line represents time to leukemia (days), the grey bars the period of treatment with nilotinib and the white bars time to death after no treatment. (C), Peripheral blood of two wild type (Wt) littermates; two overtly leukemic P190 Bcr/Abl transgenic mice before treatment and the same mice after 7 days of 75 mg/kg nilotinib treatment. Dead cells were excluded based on propidium iodide uptake and the analysis was restricted to living mononuclear cells by forward and side scatter gate settings. Antibodies are as indicated. (D), Percentage of peripheral blood cells that had cell surface expression of CD19 and high levels of AA4.1. Bars, ± SEM. Wild type, n = 3; preleukemic, n = 3; leukemic, n = 3; nilotinib-treated, n = 2.

Mentions: In this transplant model, the initiation of leukemia is synchronized and the drug is tested for effect against an initially small number of highly malignant cells. The P190 Bcr/Abl transgenic mice represent a different model of leukemia. The disease has a natural progression, starting with an initial phase in which mice are healthy. On a C57Bl/6J background, mice become overtly sick when they are, on average, 100 days old. To study the effect of nilotinib treatment on this more natural model of advanced stage leukemia, we randomly selected five P190 Bcr/Abl mice showing visible signs of lymphoma and nilotinib treatment of 75 mg/kg daily was started. Remarkably, nilotinib treatment led to a complete regression of the overt lymphomas within six days for all five Bcr/Abl transgenic mice (Fig. 3A). A significant improvement in the health of all five mice was also observed, with increased activity and restored mobility within one week of treatment. We treated the five mice for a total of 30 days (Fig. 3B). Two of the mice that were taken off treatment died 11 days later, whereas three mice survived more than 50 days without visible reoccurrence of the leukemia/lymphoma. Five additional Bcr/Abl transgenic mice were selected upon visible signs of lymphoma and were kept under observation without any treatment. All five mice in the untreated group became moribund within 3–11 days and were sacrificed according to institutional regulations (Fig. 3B).


Nilotinib treatment in mouse models of P190 Bcr/Abl lymphoblastic leukemia.

Kaur P, Feldhahn N, Zhang B, Trageser D, Müschen M, Pertz V, Groffen J, Heisterkamp N - Mol. Cancer (2007)

Analysis of nilotinib in a transgenic mouse model of terminal leukemia/lymphoma. (A), Five P190 Bcr/Abl transgenic mice were treated with 75 mg/kg nilotinib daily upon visible signs of lymphoma for a period of 30 days. This image shows one of the five mice treated with the drug. Arrows point to the dramatic reduction in the size of the lymph node swelling/lymphoma over a period of six days of treatment. (B), Survival after diagnosis of overt leukemia/lymphoma. Numbers to the left indicate individual identifiers of the transgenic mice. The arrow points to the first diagnosis of leukemia/lymphoma. The black line represents time to leukemia (days), the grey bars the period of treatment with nilotinib and the white bars time to death after no treatment. (C), Peripheral blood of two wild type (Wt) littermates; two overtly leukemic P190 Bcr/Abl transgenic mice before treatment and the same mice after 7 days of 75 mg/kg nilotinib treatment. Dead cells were excluded based on propidium iodide uptake and the analysis was restricted to living mononuclear cells by forward and side scatter gate settings. Antibodies are as indicated. (D), Percentage of peripheral blood cells that had cell surface expression of CD19 and high levels of AA4.1. Bars, ± SEM. Wild type, n = 3; preleukemic, n = 3; leukemic, n = 3; nilotinib-treated, n = 2.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2169263&req=5

Figure 3: Analysis of nilotinib in a transgenic mouse model of terminal leukemia/lymphoma. (A), Five P190 Bcr/Abl transgenic mice were treated with 75 mg/kg nilotinib daily upon visible signs of lymphoma for a period of 30 days. This image shows one of the five mice treated with the drug. Arrows point to the dramatic reduction in the size of the lymph node swelling/lymphoma over a period of six days of treatment. (B), Survival after diagnosis of overt leukemia/lymphoma. Numbers to the left indicate individual identifiers of the transgenic mice. The arrow points to the first diagnosis of leukemia/lymphoma. The black line represents time to leukemia (days), the grey bars the period of treatment with nilotinib and the white bars time to death after no treatment. (C), Peripheral blood of two wild type (Wt) littermates; two overtly leukemic P190 Bcr/Abl transgenic mice before treatment and the same mice after 7 days of 75 mg/kg nilotinib treatment. Dead cells were excluded based on propidium iodide uptake and the analysis was restricted to living mononuclear cells by forward and side scatter gate settings. Antibodies are as indicated. (D), Percentage of peripheral blood cells that had cell surface expression of CD19 and high levels of AA4.1. Bars, ± SEM. Wild type, n = 3; preleukemic, n = 3; leukemic, n = 3; nilotinib-treated, n = 2.
Mentions: In this transplant model, the initiation of leukemia is synchronized and the drug is tested for effect against an initially small number of highly malignant cells. The P190 Bcr/Abl transgenic mice represent a different model of leukemia. The disease has a natural progression, starting with an initial phase in which mice are healthy. On a C57Bl/6J background, mice become overtly sick when they are, on average, 100 days old. To study the effect of nilotinib treatment on this more natural model of advanced stage leukemia, we randomly selected five P190 Bcr/Abl mice showing visible signs of lymphoma and nilotinib treatment of 75 mg/kg daily was started. Remarkably, nilotinib treatment led to a complete regression of the overt lymphomas within six days for all five Bcr/Abl transgenic mice (Fig. 3A). A significant improvement in the health of all five mice was also observed, with increased activity and restored mobility within one week of treatment. We treated the five mice for a total of 30 days (Fig. 3B). Two of the mice that were taken off treatment died 11 days later, whereas three mice survived more than 50 days without visible reoccurrence of the leukemia/lymphoma. Five additional Bcr/Abl transgenic mice were selected upon visible signs of lymphoma and were kept under observation without any treatment. All five mice in the untreated group became moribund within 3–11 days and were sacrificed according to institutional regulations (Fig. 3B).

Bottom Line: In addition, culture of such cells ex vivo showed that they were as sensitive as the parental cell line to nilotinib but that the presence of stromal support allowed resistant cells to grow out.Visible lymphoma masses disappeared within six days of treatment and leukemic cell numbers in peripheral blood were significantly reduced.These results show that nilotinib has very impressive anti-leukemia activity but that lymphoblastic leukemia cells can become unresponsive to it both in vitro and in vivo through mechanisms that appear to be Bcr/Abl independent.

View Article: PubMed Central - HTML - PubMed

Affiliation: Section of Molecular Carcinogenesis, Division of Hematology/Oncology, Saban Research Institute, Childrens Hospital Los Angeles and the Keck School of Medicine, University of Southern California, Los Angeles, California, USA. pavinder@gmail.com

ABSTRACT

Background: Ph-positive leukemias are caused by the aberrant fusion of the BCR and ABL genes. Nilotinib is a selective Bcr/Abl tyrosine kinase inhibitor related to imatinib, which is widely used to treat chronic myelogenous leukemia. Because Ph-positive acute lymphoblastic leukemia only responds transiently to imatinib therapy, we have used mouse models to test the efficacy of nilotinib against lymphoblastic leukemia caused by the P190 form of Bcr/Abl.

Results: After transplant of 10,000 highly malignant leukemic cells into compatible recipients, untreated mice succumbed to leukemia within 21 days, whereas mice treated with 75 mg/kg nilotinib survived significantly longer. We examined cells from mice that developed leukemia while under treatment for Bcr/Abl kinase domain point mutations but these were not detected. In addition, culture of such cells ex vivo showed that they were as sensitive as the parental cell line to nilotinib but that the presence of stromal support allowed resistant cells to grow out. Nilotinib also exhibited impressive anti-leukemia activity in P190 Bcr/Abl transgenic mice that had developed overt leukemia/lymphoma masses and that otherwise would have been expected to die within 7 days. Visible lymphoma masses disappeared within six days of treatment and leukemic cell numbers in peripheral blood were significantly reduced. Treated mice survived more than 30 days.

Conclusion: These results show that nilotinib has very impressive anti-leukemia activity but that lymphoblastic leukemia cells can become unresponsive to it both in vitro and in vivo through mechanisms that appear to be Bcr/Abl independent.

Show MeSH
Related in: MedlinePlus